Bad debt in Vietnam is expected to account for about 9 percent of total loans, after careful calculations, below the 15 percent ratio estimated by Moody's Investors Service, the central bank said in a statement.

Vietnam has one of Asia's highest ratios of non-performing loans, which has squeezed the economy and led to a tightening of credit needed to boost flagging consumer spending and keep businesses afloat.

Banks in Vietnam managed to cut bad debt to 3.63 percent of loans at the end of 2013, from 4.73 percent last October, the State Bank of Vietnam said in the statement issued late on Friday after a Moody's report on Feb. 18.

The central bank revised down the 3.79 percent bad debt ratio estimated by the central bank last month.

Moody's estimated on Tuesday "problem assets in the system to comprise at least 15 percent of total assets, significantly above the 4.7 percent non-performing loan ratio reported by the State Bank of Vietnam in October 2013."

The central bank said Moody's used its own methods, criteria and information to measure Vietnam's bad debts, so they provided a different result.

"If calculating thoroughly, the ratio of non-performing loans, including the bad debt restructured under Directive 780/QD-NHNN, would just be at around 9 percent," Vietnam's central bank said, referring to a directive on classifying debts issued in April 2012. The bank did not give a time frame.

A circular guiding the implementation of the directive will take effect as of June 1, 2014, after which Vietnamese bankers have said bad debt in domestic banks would jump.

The central bank has said it aimed to solve toxic problem loans by the end of 2015. It established a company to deal away the bad debt last July.